Modeling hints: I/O operations
Adds an example showing how to model I/O operation in SimGrid. It uses data from real experiments on Grid'5000 to model the impact of concurrent operation on disks and the variability/noise in single I/O operations. Adds an entry in the doc presenting the results. The code is available at: docs/source/tuto_disk. The rst file was generated from the analysis.org file. The folder includes a dockerfile to rerun the experiment if needed.